Per Darryl's Spectacle Optics program, a 50mm diameter plano CR-39 weighs 5.3 grams, MR6 1.60 4.0 grams. However this assumes a standard center thickness of 2mm on CR-39 and 1.5 on 1.60. If one got the CR-39 down to 1.5 as well then for the same volume of material the lower density CR-39 would be lighter, ever so slightly.
Looks like not. This looks like exactly what high index are supposed to be for, that as power dramatically increases the gains in thinness overtake the losses in density. CR-39 is always the ultimate loser, but note at -12.00 (the program only goes up to 12 otherwise I would have given you your -19.00) the lightest of all, trivex, is not very light, just because a -12.00 trivex is super thick.
And bonus, this surprised me, check out how poly is even at 1.5 CT. Grind that down to 1.0 and it could end up being the lightest even at -19.00!
material |
-3.00 |
-9.00 |
-12.00 |
CR-39 |
7.9
|
14 |
18.1 |
poly |
5.6 |
10 |
12.6 |
trivex
|
5.4 |
10.1 |
13.1 |
MR6 1.60 |
6.2 |
11 |
13.8 |
MR10 1.67 |
6.1 |
10.4 |
12.8 |
1.74 |
6.3 |
10.3 |
12.6 |
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